The following paragraphs are not an admission that anything discussed in them is prior art or part of the knowledge of persons skilled in the art.
U.S. Pat. No. 4,925,358 (Cook) describes a small, self-contained portable back-hoe having a wheeled frame with a towing tongue for over-the-road trailering. Pivoted outriggers are connected to the back and a third support is secured to the front of the frame. Cylinder units are coupled to position the supports for digging and in raised position for trailering. The bucket and articulated boom assembly is affixed to the frame with a vertical pivot and includes cylinder units for digging operation thereof. An operator station and a hydraulic power supply source or system is secured to the front of the frame. A special hydraulic supply is integrated into the front framework. The back-hoe boom assembly and operating assembly are balanced about the single axle for convenient positioning. The bucket assembly and three-point support are arranged to minimize the tipping of the frame as a result of the digging forces. A gasoline driven high efficiency industrial-type pump is connected to the cylinder units with a filter and the suction side. A reservoir is built into the front frame structure and includes a watertower element to eliminate air from the hydraulic liquid. The reservoir reliably removes the air from the liquid to avoid pump malfunction.
U.S. Pat. No. 5,490,755 (Billotte) describes a self-propelled boom loader arranged as a hybrid between a trailer and a self-propelled vehicle. The loader has a carriage with a pair of independently controllable drive wheels powered by hydraulic drive motors and a free turning third wheel caster spaced from the drive wheels in a tricycle configuration. A hydraulic loader such as a knuckle boom loader is carried on the carriage on a turntable mount. The loader has an on-board hydraulic pump providing operational hydraulic pressure to the boom and turntable, which pressure is controllably divertable to operate the drive motors via controls in the loader cab. The loader is adapted for maneuvering in close quarters and has stabilizing outriggers. The drive wheels have rotationally disengageable hubs for freewheeling, and the carriage has a tow hitch coupleable to a tow vehicle for trailering, the wheels and hitch being mounted on the carriage such that the third wheel is lifted from the ground during trailering, for over the road transport.
U.S. Pat. No. 6,668,471 (Cook et al.) describes a multifunctional, self-contained towable backhoe apparatus adapted for direct over-the-road trailering by a towing vehicle, having a support frame having a front and a rear, and a trailering hitch attached to the front. Wheels support the frame at the front and the rear. The rear wheels can function as drive wheels. A backfill blade is movably attached to the rear of the frame. An articulated arm assembly is pivotably mounted on the rear of the frame. A stabilizer with a street pad, a spade, or both, can be secured to the front of the frame for stabilizing the apparatus while in a digging position. The movable backfill blade is capable of movement to a raised position for supporting the articulated arm during transport and movement to at least one lowered ground-engaging position capable of stabilizing the apparatus, of earth moving, or a combination thereof. One end of the articulated arm is adapted for attachment of a tool, including a digging bucket, a pavement breaker, an auger, a grapple, or a fork. The self-contained towable backhoe apparatus can also have a pad on the backfill blade capable of cushioning the articulated arm assembly.